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                <p>时间限制：10s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：256MB</p>			</div>
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                                <h3>题目描述</h3><p><p><span id="1386076052352S" style="display: none">&nbsp;</span><span style="font-size: medium"><font face="Times New Roman">给定一棵大小为 n 的有根点权树,支持以下操作: <br />
　　&bull; 换根 <br />
　　&bull; 修改点权&nbsp; <br />
&nbsp;&nbsp;&nbsp; 　&bull; 查询子树最小值 <br />
</font></span></p>
<p></p></p><hr/><h3>输入格式</h3><p><p><span style="font-size: medium"><font face="Times New Roman">　　第一行两个整数 n, Q ,分别表示树的大小和操作数。 <br />
　　接下来n行,每行两个整数f,v,第i+1行的两个数表示点i的父亲和点i的权。保证f &lt; i。如 果f = 0,那么i为根。输入数据保证只有i = 1时,f = 0。 <br />
　　接下来 m 行,为以下格式中的一种: <br />
　　&bull; V x y表示把点x的权改为y <br />
　　&bull; E x 表示把有根树的根改为点 x <br />
　　&bull; Q x 表示查询点 x 的子树最小值 <br />
</font></span></p>
<p><span id="1386076052487E" style="display: none">&nbsp;</span></p></p><hr/><h3>输出格式</h3><p><p><span style="font-size: medium"><font face="Times New Roman">　　对于每个 Q ,输出子树最小值。 <br />
</font></span></p>
<p align="left"></p></p><hr/><h3>样例输入</h3><pre>
3 7
0 1
1 2
1 3
Q 1
V 1 6
Q 1
V 2 5
Q 1
V 3 4
Q 1


</pre><hr/><h3>样例输出</h3><pre>

1
2
3
4

</pre><hr/><h3>提示</h3><p><p>　　对于 100% 的数据:n, Q &le; 10^5。<br />
</p></p><hr/><h3>题目来源</h3><p>没有写明来源</p>
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